It is difficult to distinguish the independent effects of gravity from those of inertia on a running animal. Simply adding mass proportionally changes both the weight (gravitational force) and mass (inertial force) of the animal. We measured ground reaction forces for eight male humans running normally at 3 m s(−)(1) and under three experimental treatments: added gravitational and inertial forces, added inertial forces and reduced gravitational forces. Subjects ran at 110, 120 and 130 % of normal weight and mass, at 110, 120 and 130 % of normal mass while maintaining 100 % normal weight, and at 25, 50 and 75 % of normal weight while maintaining 100 % normal mass. The peak active vertical forces generated changed with weight, but did not change with mass. Surprisingly, horizontal impulses changed substantially more with weight than with mass. Gravity exerted a greater influence than inertia on both vertical and horizontal forces generated against the ground during running. Subjects changed vertical and horizontal forces proportionately at corresponding times in the step cycle to maintain the orientation of the resultant vector despite a nearly threefold change in magnitude across treatments. Maintaining the orientation of the resultant vector during periods of high force generation aligns the vector with the leg to minimize muscle forces.
New funding schemes for junior faculty staff
In celebration of our 100th anniversary, JEB has launched two new grants to support junior faculty staff working in animal comparative physiology and biomechanics who are within five years of setting up their first lab/research group. Check out our ECR Visiting Fellowships and Research Partnership Kickstart Travel Grants.
JEB@100: an interview with Monitoring Editor Stuart Egginton
Stuart Egginton reveals how he overcame the challenges of being a comparative physiologist in a medical school and how he would tell his younger self to trust his instincts when pursuing new ideas.
Travelling Fellowships from JEB
Our Travelling Fellowships offer up to £3,000 to graduate students and post-doctoral researchers wishing to make collaborative visits to other laboratories. Next deadline to apply is 27 October 2023
Feedforward and feedback control in the neuromechanics of vertebrate locomotion
Auke J. Ijspeert and Monica A. Daley provide an overview of key knowledge on feedback and feedforward control gained from comparative vertebrate experiments obtained from neuromechanical simulations and robotic approaches. Read the full Centenary Review Article here.
Light fine-tunes electric fish pulses to keep them in the shade
Weakly electric fish perceive their surroundings through electric chirrups and now Ana Camargo & colleagues have revealed that light fine-tunes the fish's electric pulses to ensure that they remain scheduled beneath the mats of vegetation they use for shelter, avoiding penetrating beams of light that could give them away.
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